Circumferentially driven continuous flow centrifuge

ABSTRACT

A centrifuge ( 10 ) including a first rotatable mechanism ( 60 ) having a rotation axis with a fluid retentive housing ( 20 ) being coaxially mounted on the first rotatable mechanism for co-rotation therewith; a second rotatable mechanism ( 90 ) having a rotation axis with the first and second rotatable mechanisms being coaxially interconnected for co-rotation around a common axis; and fluid tubing ( 70 ) connected to the axis of the fluid retentive housing and having a distal length that extends axially outwardly from the fluid retentive housing. A support arm ( 50 ) is mounted to the second rotatable mechanism, a support tube ( 80 ) receives therethrough at least a part of the distal length of the fluid tubing, and a bearing member ( 82 ) rotatably supports the support tube in the support arm, whereby upon rotation of the first and second rotatable mechanisms, the fluid tubing is free to one of rotate with and rotate relative to the support tube.

BACKGROUND OF THE INVENTION

The present invention relates to centrifuge apparati and moreparticularly to a centrifuge which works in conjunction with a cassette,rotor or other device having fluid retentive chambers and fluid flowtubing fixedly attached to the axis of the device.

In the context of mechanisms which have come to be known as continuousflow centrifuges, when a length of tubing is fixedly attached to therotation axis of a device which contains the fluid material to becentrifuged, the entire length of tubing must be rotated by use ofrotary seals or some other means to avoid twisting the tubing. A wellknown method for avoiding the use of rotary seals is to curve the lengthof tubing outwardly from the axis and around the outer edge of thecircumference of the rotor, cassettes or the like and, to rotate thetubing in an orbital fashion around the rotor/cassette at one-half timesthe rotational speed of the rotor/cassette itself. Such a method foreliminating tube twisting and apparati therefore are disclosed, forexample, in U.S. Pat. Nos. 4,216,770, 4,419,089 and 4,389,206.

Problems inherent in such prior apparatuses which orbit the fluid flowtubing around the axis of centrifuge rotation are that the axis ofrotation is disposed vertically, the tubing is routed through an axialshaft and the apparatus is driven by driving an axial shaft whichrequires a high aspect ratio and an elongated shaft which limit therotational speed, render the apparatus instable and limits the abilityof the user to mount a second cassette, rotor or the like on opposingsides of the chuck component of the apparatus.

In accordance with the foregoing, reference is also made to U.S. Pat.No. 5,665,048 that provides a centrifuge for rotating a fluid retentivehousing having fluid input and output tubing fixedly connected to arotation axis of the fluid retentive housing, the centrifuge comprising:a frame; a first rotatable mechanism having a rotation axis, the fluidretentive housing being coaxially mounted thereon for co-rotationtherewith; a second rotatable mechanism having a rotation axis, thefirst and second rotation mechanism being coaxially mounted on theframe; the second rotatable mechanism having an outer circumferentialsurface engaged with a drive mechanism, the drive mechanism driving theouter circumferential surface such that the second rotatable mechanismrotates at a selected rotational speed X; the first rotatable mechanismbeing interconnected to the second rotatable mechanism such that thefirst rotatable mechanism rotates simultaneously with the secondrotatable mechanism at a rotational speed of 2X.

The second rotatable mechanism includes a seat for holding a distallength of the output tubing which extends from the axis of the fluidretentive housing, wherein the distal length of the output tubing heldby the seat is rotated around the rotation axis at the same rotationalspeed as the second rotatable mechanism. One of the problems associatedwith such an arrangement is that there is continuous friction betweenthe tubing and the seat.

SUMMARY OF THE INVENTION

Therefore, in accordance with the present invention, there is providedan improvement in a centrifuge, and, in particular, an improvementrelating to fluid tubing by the support thereof. In accordance with thepresent invention, there is provided a centrifuge for rotating a fluidretentive housing such that one or more selected materials suspended ina fluid retained within the housing centrifuged upon rotation of thehousing. The centrifuge includes a first rotatable mechanism having arotation access with the fluid retentive housing being coaxially mountedon the first rotatable mechanism for co-rotation therewith. There isalso provided a second rotatable mechanism having a rotation axis withthe first and second rotatable mechanisms being coaxially interconnectedfor co-rotation around a common axis. Fluid tubing connected to the axisof the fluid retentive housing has a distal length that extends axiallyoutwardly from the fluid retentive housing. In accordance with oneembodiment of the present invention, the improvement comprises a supportarm mounted to the second rotatable mechanism, a support tube forreceiving therethrough at least part of the distal length of the fluidtubing, and a bearing member for rotatably supporting the support tubein said support arm whereby upon rotation of the first and secondrotation mechanisms, the fluid tubing is free to either rotate with orrotate relative to the support tube so as to minimize friction betweenthe fluid tubing and the support therefor.

In accordance with another embodiment of the present invention, there isprovided a multi-lumen rope comprising a plurality of elongated tubesfor delivering one or more fluids between a first fluid containingmechanism and a fluid receiving rotatably driven rotor. One end of therope is attached to the center of the driven rotor and the other end ofthe rope is attached to the first fluid retaining mechanism. The firstfluid retaining mechanism is mounted on an opposing side of the rotorsuch that the point of attachment of the other end of the rope issubstantially coaxial with an axis of the rotor. The aforementionedelongated tubes may comprise at least one tube disposed of in a spiralwrap. This may be either a single strand or a multi-strand wrap and maybe either in a counterclockwise or clockwise direction. And also, in asingle strand or a multi-strand, at one end the spiral wrap may beclockwise while at the other end counterclockwise and also optionallyhave a straight section therebetween.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a centrifuge apparatus according to theinvention;

FIG. 2 is a perspective view of a portion of the apparatus of FIG. 1,particularly, the support arm;

FIG. 3 is an exploded perspective view showing the support arm with endguides and the fluid retentive housing with fluid tubing;

FIG. 4 is an exploded perspective view showing the components of thefluid retentive housing and fluid tubing; and

FIGS. 5A-5H disclose various separate embodiments of the fluid tubing ormulti-lumen rope as in accordance with the present invention.

DETAILED DESCRIPTION

FIG. 1 shows a centrifuge apparatus 10, the basic construction of whichmay be substantially the same as that described in U.S. Pat. No.5,665,048. As far as the invention of the present invention isconcerned, this relates more to the tubing 70, and, in particular, itssupport from the centrifuge apparatus 10. The support includes thesupport arm 50 as well as its guide members 52 and 54.

As indicated previously, the basic structure of the centrifuge apparatus10 may be the same as that described in U.S. Pat. No. 5,665,048. U.S.Pat. No. 5,665,048 is thus hereby now incorporated by reference herein.This apparatus includes a bag set 20. This may also be referred to as aself-contained fluid retentive centrifuge cassette or rotor which ismounted on an inner-rotatable chuck 60. The bag set 20, as illustratedin FIGS. 1 and 3, has fluid input and output 70 coaxially and fixedlyattached to the axis 40 of the cassette 20. As shown, the cassette ismounted on the chuck 60 such that it's rotation axis is coaxial alongcommon axis 40. Thus, as the chuck 60 rotates, the fixedly attachedtubing 70 co-rotates therewith. As shown, there is a length 72 of thetubing 70 which extends axially outwardly from the area of the fixedattachment 71. The length 72 of tubing is curved axially backwardlytoward and extends through a radially outer, separately rotatable pulley90 which rotates, by virtue of a gear train interconnecting the pulley90 and the chuck 60 at a speed of XRPM while the chuck rotates at aspeed of 2XRPM. Again, reference is made to U.S. Pat. No. 5,665,048which is incorporated by reference herein regarding the operation of thechuck and pulley arrangement. FIG. 1 actually shows the cutaway sectionindicating the chuck 60 and a further cutaway section showing a gear 91,part of the aforementioned gear train.

In operation, as the pulley 90 rotates, the backwardly curved length 72of the tubing is rotated around axis 40 at a rate of XRPM while thefixedly attached end 71 of the tubing 70 is actually rotated at a rateof 2XRPM. This phenomenon is well known in the art as enabling thetubing 70 to avoid twisting around its axis even as the cassette 20 andthe chuck 60 forced the tubing 70, 71 to be axially rotated. A fullerdescription of this phenomenon is described in U.S. Pat. No. 5,665,048as well as in U.S. Pat. No. RE29,738 (U.S. Pat. No. 3,586,413) (Adams).

Now, reference is further made to FIGS. 2 and 3 which illustrate thesupport arm 50. The support arm 50 at its central section 56, is fixedlyattached to an inner-periphery of the pulley 90. Thus, the support arm50 rotates with the Hub 90.

The support arm 50 is of elongated shape and extends on either side ofthe centrifuge apparatus 10, as illustrated in FIG. 1. As illustrated inFIG. 2, the support arm 50 has an elongated channel 58 which receivesthe support tube 80. The support tube 80 is actually supported in thechannel 58 by means of a pair of bearings 82 illustrated in FIGS. 3 and4. Each of these bearings is accommodated in a corresponding recess 84at opposite ends of the support arm, as illustrated in FIG. 2.

Thus, the support arm 50 is fixedly attached to the pulley 90, thesupport tube 80 is supported within the channel and support arm by meansof bearings 82 and then the fluid tubing 70 extends through the supporttube 80, but in this regard, FIG. 1 shows all of these variouscomponents in their final assembled state. The fluid tubing 70 is shownbeing guided by a C-shaped guide member 52 into one end of the supporttube 80. At the other end of the support tube, the fluid tubing length72 extends out of the support tube and into the S-shaped tubing guide54, as also illustrated in FIG. 1.

When the fluid tubing is in the form of a multi-lumen rope, embodimentsof which will be described hereinafter, the elements of the ropefurthest from the access of rotation exert large forces against thesupporting surface and consequently produce large frictional forcesimpeding the twists required to make the slip rope function. It has beenfound that the following perimeters are desirable for proper operationof a multi-lumen skip rope;

1) strong but flexible skip rope assembly;

2) ability to transmit torque without damage to the rope;

3) low friction between rope and supports particularly far from therotational axis where the g-field is high.

Parameters 1 and 2 are generally met by selecting relatively smalldiameter, high durometer thermoplastic tubing. Gluing methods andfixtures were used so that an assembly of at least 9 lumens could bewell fabricated with very uniform tubing lay and therefore stiffness andstrength. This assembly is of a spiral wrapped construction to improveuniformity.

Reference is also now made to FIGS. 5A-5H for various designs of therope. FIG. 5A shows a single strand 100A counterclockwise wrap whileFIG. 5B shows a multi-strand 100B counterclockwise wrap. FIG. 5C shows asingle strand 100C clockwise wrap, while FIG. 5D shows a multi-strand100D clockwise wrap. Through testing and observation, it is found thatthe two ends of the skip rope behave asymmetrically. This is due to thefact that one end is twisting clockwise and the other endcounterclockwise. One end tends to twist up while the other enduntwists. Thus, it has been found that in accordance with oneembodiment, during the rope fabrication, the twist direction may bereversed in mid-rope. In this regard, refer to FIGS. 5A, 5F and 5H. Itis noted that a small section of the rope in the middle has no twist. Bydoing so, one may install the rope so that both ends see the sametwisting condition. The rope may be installed so that both ends twist upto yield maximum torque stiffness so that both ends untwist to produceminimum restriction to fluid flow in the tubes.

In accordance with the present invention, in order to provide thedesired low friction, relating to the fluid tubing, it is noted thatportions of the skip rope progress through curved supports from theaccess of rotation from the periphery where the rope is guided throughvery smooth, Teflon, hard coated aluminum parts. Please refer to FIG. 3and guide members 52 and 54. That in these areas, the co-efficient offriction between the skip rope and the guides is preferably less than0.2.

The portion of the skip rope at the maximum radius from the center ofrotation is a straight section of various lengths. This section can bevery important to the overall torque needed to twist the rope. Indeedthe weight of the skip rope assembly (plus fluids if it is filled) isincreased by the G-field which may be a multiplier of 1,000 or more. Toreduce the torque needed to drive the twisting motion, this section ofskip rope is supported by the aforementioned support tube 80. This ispreferably a stiff tube of either metal of structural plastic. The stifftube is itself supported by the aforementioned low friction bearings 82allowing full rotation about its own axis. This reduces the torqueneeded to drive this region of the skip rope assembly to very nearlyzero. This structure of the support tube and bearings, provides anadvantageous support for the length of fluid tubing or lumen between theguides 52 and 54. Because the support tube is free to rotate, uponrotation of the members such as 60 and 90 in FIG. 1, in other wordsfirst and second rotation mechanisms, the fluid tubing is free to eitherrotate with or rotate relative to the support tube.

Another characteristic of the present invention relates to theconstruction of the multi-lumen rope itself, as illustrated, forexample, in FIG. 5B. This may be comprised of a plurality of at leasteight lumens 100B about a center lumen 102B. The center lumen 102B isstraight while the other peripheral lumens wrap, such as illustrated inFIG. 5B. The center lumen 102B may be an expresser tube while the lumens100B may be processing tubes. Put another way, the tube 102B may be aninput tubing and tubings 100B may be output tubings. The input andoutput tubings may be also reversed.

It will now be apparent to those skilled in the art that otherembodiments, improvements, details and uses can be made consistent withthe letter and spirit of the foregoing disclosure and within the scopeof this patent, which is limited only by the following claims, construedin accordance with the patent law, including the doctrine ofequivalents.

1. In a centrifuge for rotating a fluid retentive housing such that oneor more selected materials suspended in a fluid retained within thehousing are centrifuged upon rotation of the housing, said centrifugeincluding: a first rotatable mechanism having a rotation axis with thefluid retentive housing being coaxially mounted on the first rotatablemechanism for co-rotation therewith; a second rotatable mechanism havinga rotation axis with the first and second rotatable mechanisms beingcoaxially interconnected for co-rotation around a common axis; fluidtubing connected to the axis of the fluid retentive housing and having adistal length that extends axially outwardly from the fluid retentivehousing; the improvement comprising; a support arm mounted to the secondrotatable mechanism, a support tube for receiving therethrough at leastpart of the distal length of said fluid tubing, and a bearing member forrotatably supporting said support tube in said support arm, whereby uponrotation of said first and second rotation mechanisms said fluid tubingis free to one of rotate with and rotate relative to said support tube.2. In a centrifuge as set forth in claim 1, wherein said support armextends to either side of said first and second rotatable mechanisms. 3.In a centrifuge as set forth in claim 1, wherein said support armincludes a longitudinal channel for receiving said support tube.
 4. In acentrifuge as set forth in claim 3, wherein said support arm alsoincludes oppositely disposed recesses for receiving said bearing member.5. In a centrifuge as set forth in claim 4, wherein said bearing membercomprises a pair of oppositely disposed bearings received in saidrecesses of said support arm and for supporting opposite ends of saidsupport tube.
 6. In a centrifuge as set forth in claim 5, including aninput guide member secured to one side of said support arm.
 7. In acentrifuge as set forth in claim 6, including an output guide membersecured to an opposite end of said support arm.
 8. In a centrifuge asset forth in claim 1, including an input guide member secured to oneside of said support arm.
 9. In a centrifuge as set forth in claim 8,including an output guide member secured to an opposite end of saidsupport arm.
 10. In a centrifuge as set forth in claim 1, wherein saidfluid tubing comprises a high durometer urethane tubing.
 11. In acentrifuge as set forth in claim 1, further including guide members atboth ends of said support arm.
 12. In a centrifuge as set forth in claim11, wherein said pair of guide members are each smooth, Teflon,hardcoated, aluminum members.
 13. A multi-lumen rope comprising aplurality of elongated tubes for delivering one or more fluids between afirst fluid containing mechanism and a fluid receiving rotatably drivenrotor, one end of the rope being attached to the center of the drivenrotor, the other end of the rope being attached to the first fluidretaining mechanism, the first fluid retaining mechanism being mountedon an opposing side of the rotor and such that the point of attachmentof the other end of the rope is substantially coaxial with an axis ofthe rotor, said elongated tubes comprising at least one tube disposed ina spiral wrap.
 14. A multi-lumen rope as set forth in claim 13, whereinsaid plurality of tubes include a center expresser tube and a pluralityof peripheral processing tubes.
 15. A multi-lumen rope as set forth inclaim 14, wherein said spiral wrap is counterclockwise.
 16. Amulti-lumen rope as set forth in claim 14, wherein said spiral wrap isclockwise.
 17. A multi-lumen rope as set forth in claim 13, wherein oneend of the rope has a right hand twist and the other end of the rope hasa left hand twist.
 18. A multi-lumen rope as set forth in claim 17,wherein a section of the rope in the middle has no twist.
 19. Amulti-lumen rope as set forth in claim 13, wherein the rope is installedso that both ends twist up to yield maximum tortional stiffness.
 20. Amulti-lumen rope as set forth in claim 13, wherein the rope is installedso that both ends untwist to produce minimum restriction to fluid flowin the tubes.
 21. A multi-lumen rope comprising a plurality of elongatedtubes for delivering one or more fluids between a first fluid containingmechanism and a fluid receiving rotatably driven rotor, one end of therope being attached to the center of the driven rotor, the other end ofthe rope being attached to the first fluid retaining mechanism, thefirst fluid retaining mechanism being mounted on an opposing side of therotor and such that the point of attachment of the other end of the ropeis substantially coaxial with an axis of the rotor, a support armrotatable with the rotor, a support tube for receiving therethrough atleast part of the distal length of the elongated tubes, and a bearingmember for rotatably supporting said support tube in said support arm.22. A multi-lumen rope as set forth in claim 21, wherein said supportarm has a channel for receiving said support tube and opposite recessesfor receiving a pair of bearings that comprise said bearing member. 23.A multi-lumen rope as set forth in claim 22, further including an inputguide member secured to one end of said support arm and an output guidemember secured to the other end of said support arm.
 24. A centrifugefor rotating a fluid retentive housing having fluid input and outputtubing fixedly connected to a rotation axis of the fluid retentivehousing, the centrifuge comprising: a frame; a first rotatable mechanismhaving a rotation axis and a first diameter, the fluid retentive housingbeing coaxially mounted on the first rotatable mechanism for co-rotationtherewith; a second rotatable mechanism having a rotation axis and asecond diameter greater than the first diameter, the first and secondrotatable mechanisms being coaxially mounted on the frame; the secondrotatable mechanism having an outer circumferential surface engaged witha drive mechanism, the drive mechanism driving the outer circumferentialsurface such that the second rotatable mechanism rotates at a selectedrotational speed X; the first rotatable mechanism being interconnectedto the second rotatable mechanism such that the first rotatablemechanism rotates simultaneously with the second rotatable mechanism ata rotational speed of 2X, a support arm mounted to the second rotatablemechanism, a support tube for receiving therethrough at least part ofthe distal length of said fluid tubing, and a bearing member forrotatably supporting said support tube in said support arm, whereby uponrotation of said first and second rotation mechanisms said fluid tubingis free to one of rotate with and rotate relative to said support tube.25. In a centrifuge as set forth in claim 24, wherein said support armhas a channel for receiving said support tube and opposite recesses forreceiving a pair of bearings that comprise said bearing member.
 26. In acentrifuge as set forth in claim 25, further including an input guidemember secured to one end of said support arm and an output guide membersecured to the other end of said support arm.